1. Field of the Invention
The present invention relates to an imaging apparatus and a control method for same.
2. Description of the Related Art
Conventionally, in an imaging apparatus such as a digital camera and a video camera and the like, a stepping motor is used in order to drive the lenses and the like that form a lens barrel quickly and precisely. As a method for rotationally driving this stepping motor at a high speed, a control method is known in which a position detecting apparatus such as an encoder and the like is provided on the motor, and closed loop control (advance angle control) is carried out.
In the case in which the stepping motor is driven at a speed that is equal to or greater than a self-activation area, an acceleration-deceleration operation is required. At this time, in the case in which the positioning of an object is carried out using the number of revolutions of a motor, the amount of movement required for the acceleration-deceleration operation must be taken into consideration. Japanese Patent No. 4,165,915 discloses a method in which, depending on the amount of movement, the drive control of the stepping motor is switched between open loop control and closed loop control.
However, a method in which switching between open loop control and closed loop control is carried out depending only on the amount of movement is not suitable for driving in which high position precision is required, such as contrast AF (autofocus) processing in an imaging apparatus.